This invention relates to novel 5-fluorouridine, 2'-deoxy-5--fluorouridine and 1-carbamoyl-5-fluorouracil derivatives which have an antitumor effect and are available as a medicine.
A 5-fluorouracil, an antitumor agent synthesized by Duschinsky in 1957, has a wide antitumor spectrum so that it has been used clinically. However, its antitumor activity is insufficient and it has potent toxicity, thus it cannot be necessarily said to be a satisfactory pharmaceutical.
Thus, in order to decrease toxicity possessed by the 5-fluorouracil, 1-(2-tetrahydrofulyl)-5-fluorouracil (general name: Tegafur), 1-n-hexylcarbamoyl-5-fluorouracil (general name: Carmofur), 5'-deoxy-5-fluorouridine (general name Doxifluridine), etc. have been found, but it has been said that their antitumor effects are inferior to that of 5-fluorouracil.
Also, in order to improve the antitumor effect, many attempts to make various derivatives of 5-fluorouridine and 2'-deoxy-5-fluorouridine (e.g. Japanese Provisional Patent Publications No. 77298/1981, No. 92299/1981, No. 91997/ 1982, No. 91998/1982, No. 49315/1983 and No. 134397/1986) have been made, but an available one has not yet been obtained.
Further, regarding providing 1-carbamoyl-5-fluorouracil derivatives which have similar a chemical structure in a part thereof of the compounds of present invention, many attempts have been made as in Japanese Provisional Patent Publications No. 81865/1980, No. 258367/1987 and No. 204171/1986, but a effective one has not yet been obtained.